低管电压、等渗低浓度对比剂在头颈部CTA中的临床应用

Clinical application of istonic low concentration contrast agent based on low tube voltage technique in head and neck CT angiography

目的:探讨"双低"扫描技术(低管电压及低浓度对比剂)在头颈部CTA中的临床应用价值。方法:选取行头颈部CTA检查的患者60例,随机分为A、B、C 3组,每组各20例,A、B为低浓度对比剂组:对比剂为碘克沙醇(碘浓度为270mg I/m L),A组管电压80 k V,B组管电压100 k V;C组为常规高浓度对比剂对照组:对比剂为碘帕醇(碘浓度为370 mg I/m L),管电压为120 k V;3组管电流均采用350 m A。对比3组中主动脉、颈总动脉、颈内动脉、大脑中动脉的CT值及颈总动脉信噪比(SNR)、对比噪声比(CNR)值,同时测量患者接受的辐射剂量、碘摄入量。结果:所有患者的颈动脉及其分支均可清晰显示,主动脉、颈总动脉、颈内动脉、大脑中动脉的CT值分别为:A组(541.37±53.23、612.28±71.69、575.94±75.09、348.11±27.07)HU,B组(470.75±66.32、557.00±95.48、533.75±65.00、314.00±44.29)HU,C组(423.05±30.02、539.66±66.38、488.38±43.89、294.05±27.23)HU,3组中各支动脉CT值差异无统计学意义(P>0.05);有效辐射剂量(ED)分别为A组(0.43±0.10)m Sv,B组(0.87±0.44)m Sv,C组(1.45±0.15)m Sv,组间差异有统计学意义(P<0.05);总碘量分别为A组(20 970.00±679.49)mg,B组为(20 790.00±714.35)mg,C组为(28 736.67±931.15)mg,A、B组均显著低于C组(P<0.05);A、B、C 3组颈总动脉的SNR值分别为51.19±7.05、49.81±8.19、68.80±5.66,CNR值分别为45.32±8.01、43.90±7.60、58.46±5.12,差异有统计学意义(P<0.05);3组图像的主观评分A组为(3.65±0.59)分,B组为(3.80±0.41)分,C组为(3.90±0.31)分,差异无统计学意义(P>0.05),3组图像均能满足诊断要求。结论:双低CTA检查能在较大幅度降低碘摄入量及辐射剂量的同时获得临床满意的图像,合适管电压的选择应结合患者的体重指数(BMI)。

Objective： To investigate the clinical value of double low scanning technique（ low tube voltage and low concentration contrast agent） in head and neck CT angiography（ CTA）. Methods： 60 patients underwent head and neck CTA examination were randomly divided into A,B and C group,with 20 patients in each group. A,B were low concentration contrast agent group（ iodixanol,with iodine concentration of 270 mg/m L）,group A received tube voltage 80 k V,group B received tube voltage 100 k V,group C was conventional high concentration contrast agent group（ iopamidol,with iodine concentration of 370 mg I/m L）,tube voltage was 120 k V,the tube current were 350 m A in three groups. CT values of aorta,common carotid artery,internal carotid artery and middle cerebral artery and were measured,signal-to-noise ratio（ SNR）,contrast-to-noise ratio（ CNR） of carotid artery were compared between the three groups.Radiation dose and iodine intake were measured at the same time. Results： All the branches in head and neck artery were clearly displayed. The CT values of aorta,common carotid artery,internal carotid artery and middle cerebral artery were： 541. 37 ± 53. 23,612. 28 ± 71. 69,575. 94 ± 75. 09 and 348. 11 ± 27. 07 HU in group A,470. 75 ± 66. 32,557. 00 ± 95. 48,533. 75 ± 65. 00 and314. 00 ± 44. 29 HU in group B,and 423. 05 ± 30. 02,539. 66 ± 66. 38,488. 38 ± 43. 89 and 294. 05 ± 27. 23 HU in group C,respectively. There was no significant difference in the CT value of each branch artery between the three groups（ P〉0. 05）. The effective radiation dose（ ED） was 0. 43 ± 0. 10 msv in group A,0. 87 ± 0. 44 msv in group B,and 1. 45 ± 0. 15 msv in group C,the differences between the three groups were statistically significant（ P〈0. 05）. The total amount of iodine for group A was（ 20 970. 00 ± 679. 49） mg,and 20790. 00 ± 714. 35 mg and 28 736. 67 ± 931. 15 mg for group B and C,the total amount of iodine in group A and B were significantly lower than that of group C（ P〈0. 05）. For groups A,B and C,the SNR and CNR in carotid artery were,51. 19 ± 7. 05,49. 81 ±8. 19,68. 80 ± 5. 66 and 45. 32 ± 8. 01,43. 90 ± 7. 60,58. 46 ± 5. 12,respectively,the differences were statistically significant（ P〈0. 05）. Subjective scores of groups A,B and C were 3. 65 ± 0. 59,3. 80 ± 0. 41 and 3. 90 ± 0. 31,the difference was not significant（ P〉0. 05）. Conclusion： The double low CTA can reduce iodine intake and radiation dose while achieving a satisfactory image. The choice of appropriate tube voltage should be based on the patient＇s body mass index（ BMI）.